Mechanical telephone



(No Model.)

J. P. SUNDERLAND.

MECHANICAL TELEPHONE.

No. 373,862. I Patented Nov. 29 1887.

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UNITED STATES PATENT OF ICE.

JOHN P. SUNDERLAND, OF BROOKLYN, NEW YORK.

MECHANICAL TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 373,862, dated November 29, 1887.

Serial No.228.1l38. ("No model.)

To all whom it may concern.-

Be it known that 1,.I0HN P. SUNDERLAND, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Mechanical Telephones, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates tov mechanical telephones, or that class of telephones or similar devices for conveying sound or articulate speech, in which the vibrations are conveyed over cords,wires, or similar connections without the aid of the electric current.

The invention consists in the peculiar construction, connection, and combination of parts, hereinafter set forth.

Figure 1 is a rear view of one of my telephones, the rear plate of the casing being removed. Fig. 2 is a vertical central section through one of the implements. Fig. 3 is a diagrammatic illustration of a double telephone-circuit. Fig. 4 is a section of the insulator.

A indicates the inclosing frame or casing, across which the diaphragm B is stretched and firmly held. The binder C is connected to the diaphragm at the center, as usual, having a button, D, in front. The binder Chas a loop or eye, E, at its rear end. The'wire F,which may be any of the wellknown wires, cables, or cords used with this class of instruments, passes through the loop E of the binder and extends from the bottom or from one side of easing A, and is secured at its end to an insulator, G, which is attached by a shackle, H, consisting of two eyebolts embracing the core and passing through the casing; or the insulator may be held in other suitable manner to one side of the casing A, (the top side, as shown in Figs. 1 and 2.) The insulator G consists of a supporting-core, K, held by the shackle, a piece of rubber tubing, L, surrounding said core K, and a band, M, around the rubber tubing. To this band M the wire F is firmly attached. The passage N in casing A, through which wire F passes, and the insulator G at the opposite side of the casing are a little farther removed from the diaphragm-face of the casing than the length of binder 0. As the wire F passes freely through the loop E of binder C, any tension applied to the wire will draw upon the binder G and so upon diaphragm B, keeping the latter always taut, while at the same time the pull of the wire is largely on the casing, (through the instrumentality of the insulator and shackle,) and only indirectly on the diaphragm through the looped binder. This mode of stretching the diaphragm and connecting it to the line-wire I believe to be novel, and it is superior to any other known to me.

The diaphragm B consists of an inner plate or disk of plaited wood or straw-board, faced on each side with a thickness of leatheroid,

and thoroughly waterproofed on both surfaces. This makes a diaphragm of great strength, which is extremely sensitive and but little affected by climatic changes. The leatheroid I have used and found to answer a good purpose is manufactured by the Leatheroid Manufacturing Company, of Kennebunk, Maine, under Patent No. 198,382, of December 18, 1877, and is described in said patent, the general features of the material being that it is a vegetable fiber treated with sulphuric acid and dextrine until it assumes a leather-like character, and is sometimes called vegetable parchment.

Two or more lines in proximity to each other may be connected by a bar or rod, as 1?, and a connection thus made throws all the telephones into circuit with each other. A convenient form of connection is shownin Fig. 3,

thesame being a metal bar with a curved portion at each end; but a tube or wire may be used to connect the two lines. I have tested the device by connecting two wires of long circuit by laying a brass tube across the wires where they came near together, and find the operation to be excellent and the communication as complete as if the connection were direct from any telephone to any other in the circuit.

I claim- 1. The combination, in a mechanical telephone, of a diaphragm, a short binder attached to said diaphragm, and a line-wire secured at its end at one side of the casing and passing through the binder, whereby when the linewire is drawn taut the direct pull will be on the casing and only an indirect strain will be placed on the binder and diaphragm.

2. The combination, with the casing of a 4. The combination,with the wires of a plurality of mechanical telephones, of a metallic coupling having hooked ends adapted to rest looselyon the wires, as set forth.

5. The diaphragm of a mechanical telephone, consisting of a central ply of wood or 20 straw-board and surface-plies of leatheroid, (a vegetable parchment formed from vegetable fiber in the manner described) the same being coated with a water-proof compound, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

JOHN P. SUNDERLAND.

Witnesses:

W. A. BARTLETT, PHILIP MAURO. 

